CPU: Cyrix with Extended MMX Instruction Set
Type of Instruction: User

Instruction: PADDSIW dest, src

dest[15..0] <- SaturateToSignedWord(dest[15..0] + src[15..0]
dest[31..16] <- SaturateToSignedWord(dest[31..16] + src[31..16]
dest[47..32] <- SaturateToSignedWord(dest[47..32] + src[47..32]
dest[63..48] <- SaturateToSignedWord(dest[63..48] + src[63..48]

Notes: This instruction adds the signed words of the source operand to
the signed words of the destination operand and writes the results to
the implied MMX register. The purpose of this instruction is the same
as the PADDSW instruction, except that it preserves both source
The DEST must be an MMX register. The SRC can be either an MMX
register or a 64-bit memory operand. The destination is an MMX register
which depends on the DEST.

Flags Affected: None


RM PM VM SMM Description
#GP(0) If Illegal memory operands EA in CS,DS,ES,FS,GS
#SS(0) If Illegal memory operands EA in SS
#PF(fcode) If page fault
#AC #AC If unaligned memory reference then alignment
check enabled and in ring 3.
#UD #UD #UD #UD If CR0.EM = 1
#NM #NM #NM #NM If CR0.TS = 1
#MF #MF #MF #MF If pending FPU Exception
#13 #13 If any part of the operand lies outside of the
EA space from 0 to FFFFH
COP & Times:

PADDSIW mm,mm/m64 0FH 51H PostByte

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